Just ran a live test for a secondary (well not really 2ndary ...have 20 blogs under this admin account), here's the result:
Choose an upfront blog template first so that lead creating a link:
Choose a bottom tier package which DID NOT allow for the theme that was associated with blog_template=6
made the payment, that went through (GREAT)
But after payment went through, resulting screen was a page that looks like the normal pro-sites listing of the possible plans to choose from with no reference to the facet that I just created a site, nor any listings of my sites..
So a couple things that demonstrate a big GAP in the design of this work flow (but easy to solve if there is anybody actually working on this project...which given the amount of bugs I have reported with solutions and no releases I am guessing there is not):
#1) There needs to be an "if statement" to check if the selected blog template allows for the presented levels and to gray out or have some sort of message on the level if that level doesn't allow for the selected blog template.
#2) There needs to be a signal to the pro-sites url after the payment is posted telling it that the user just signed up, here is the blog id ie (https://networkname.com/pro-site/?action=payment_new_site_success&id=32
pro-site can look for this and make a better landing page for after a successful signup.
Cause right now...its a very confusing cluster f*ck and embarrassing.
Hope that helps. Si se puedes!